TWENTY-NINTH ANNUAL MEETING. eit 
THE MENTOR BEDS. 
By A. W. JonzEs, Salina, Kan. Read before the Academy January 1, 1897. 
The First Biennial Report of the Kansas State Board of Agriculture contains 
an article on the geology of Kansas, by that distinguished pioneer geologist, Prof. 
B. F. Mudge. 
In this article Professor Mudge stated that the fossils of the Dakota consisted 
of a few remains of fish and saurians, dicotyledonous plants, and a few marine 
mollusks,* which he stated in a following paragraph were found in only three 
localities: two in western Saline county, near Bavaria, and one in Clay county. 
This was to me the first mention of this very interesting and apparently limited 
formation, that has since been written up under the name ‘‘ Mentor Beds’’ by 
Prof. F. W. Cragin, of Colorado College, and published in the American Geolo- 
gist. Later in the same article Professor Mudge accounts for the peculiar dis- 
tribution of the fossil vegetation in the Dakota by stating that the forests were 
probably on small islands surrounded by shallow seas; and, taking this for 
granted, I naturally concluded that at the same time that the fossil leaves were 
formed in the sand and mud of the island shores the fossil mollusks were formed 
in the surrounding seas. But some eight years ago I made a collecting trip in 
the vicinity of Brookville, and by mere chance stopping at a farmhouse for 
water where a well had been recently dug on a hillside, I was much interested in 
finding a quantity of the shell-bearing stone lying about that had been thrown 
out in digging the well. Upon inquiring, I was told that a layer of it about four 
feet in thickness had been penetrated at a depth of about 40 feet; and on the 
same hill a short distance above the well I found leaf-bearing Dakota sandstone. 
This and subsequent observations on several outcrops of the shell-bearing 
stone caused me to think that it might be a distinct formation underlying the 
Dakota. During the summer of 1895, Prof. F. W. Cragin, of Colorado, called upon 
me, and I drove out with him to examine some outcrops of this formation. Pro- 
fessor Cragin had previously visited other localities in the county, and had become 
convinced that it was a formation distinct from and underlying the Dakota. In 
the course of conversation the subject of a suitable name was discussed and the 
name of Mentor was fixed upon, the little village of Mentor being near the center 
of the best exposures, although the village is situated in the broad valley of the 
Smoky Hill river, and no well-defined outcrops of it occur within three miles of 
the station. The Mentor is found in more or less abundance over the greater 
part of Saline county. It is to my certain knowledge clearly defined in 12 of 
the 20 townships, and I think a careful investigation will reveal its occurrence in 
nearly every one. It is also found over a large area in northern McPherson 
county, and to some extent in Ellsworth, Lincoln, Ottawa and Clay counties, 
and probably exists in Marion and Dickinson counties. 
The fossiliferous strata of the Mentor consist of ferruginous and arenaceous 
sandstones, yellow, red, brown, or black in color, usually soft and friable, gener- 
ally well filled with internal and external casts of shells with the shell material 
usually entirely obliterated, although in some instances traces of pearl remain. 
In several instances, however, I have noted outcrops that had the appearance 
of the typical ‘‘ Mentor’’ stone, which required some diligent searching to reveal 
any fossils. 
*The mention of fish and saurian fossils in the Dakota by Professor Mudge was based upon 
the reports of others, and was erroneous. No such fossils have been found in the Dakota. 
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